Liquid crystal displays (LCDs) continue to improve in cost and performance, becoming a preferred display type for many computer, instrumentation, and entertainment applications. Typical LCD mobile phones, notebooks, and monitors include a light guide plate for receiving light from a light source and redistributing the light more or less uniformly across the light guide plate. Conventional light guide plates use diffusive micro-lenses to extract light. Diffusive micro-lenses are printed dots, or created by laser ablation. Diffusive micro-lenses are not particularly effective in light extraction, however, they are effective in hiding cosmetic defects inherent in a process of making light guide plates. A more efficient type of light guide plates use micro-lenses having an optical surface. They typically produce ten percent or higher luminance than conventional diffusive light guide plates.
U.S. Publication No. 2011-0242851 discloses a flexible light guide plate having micro-lenses of optical surface. They can be made through the extrusion roll molding process. While this type of light guide plate is easy to make in mass production and efficient in light extraction, it may have undesirable subtle stripes (referred herein as “banding” or “banding defects”) under certain lighting conditions.
Thus, while there have been solutions proposed for a particular light guide plate and a method for making the particular light guide plate, there remains a need for a thin light guide plate that can be easily made and have reduced level of banding defects.